Of the trace metals, zinc is the second most abundant metal in the human body, catalyzing nearly every bio-process directly or indirectly through inclusion in many different metalloenzymes. The critical role zinc plays can be discerned from the symptoms of dietary deficiency, which include dermatitis, anorexia, alopecia and impaired overall growth. Zinc appears especially important to skin health and has been used (typically in the form of zinc oxide or calamine) for over 3000 years to control a variety of skin problems. Recent data more specifically points to the healing and repairing properties of topical zinc treatment to damaged skin, often resulting in increased rates of healing. There is a growing body of biochemical support for this phenomenon. Since dandruff has been previously shown to represent significant damage to scalp skin, topical zinc treatment could aid in the repair process.
Inorganic salts, such as zinc hydroxycarbonate and zinc oxide, have been employed as bacteriostatic and/or fungistatic compounds in a large variety of products including paints, coatings and antiseptics. However, zinc salts do not possess as high of a level of biocidal efficacy as might be desired for many anti-dandruff and skin care applications.
Despite the options available, consumers still desire a shampoo that provides superior anti-dandruff efficacy versus currently marketed products; as such consumers have found that dandruff is still prevalent. Such a superior efficacy can be difficult to achieve.